In inserting a catheter into a living body lumen such as a digestive tract and a blood vessel, a guide wire is used to guide the catheter to a target site in the body lumen. The guide wire is used in the state of being inserted in the catheter.
In addition, observation or treatment of a living body lumen or the like by use of an endoscope is also performed, and a guide wire is also used to guide the endoscope or a catheter inserted in the lumen of the endoscope to a target site in the body lumen or the like.
A guide wire of this kind has been proposed in which the guide wire has a resin coating layer at a distal section of a wire body. An example of such a guide wire is disclosed in Japanese Patent Laid-Open No. Hei 10-118005. The resin coating layer makes it possible, in inserting the guide wire into a blood vessel or the like, to prevent the blood vessel wall from being damaged due to contact of the guide wire with the blood vessel wall, whereby safety is enhanced.
In such a conventional guide wire, however, a step is formed between a proximal section of the resin coating layer and the wire body, so that the proximal end part of the resin coating layer may be caught by a medical implement used in combination with the guide wire, specifically the distal end of a catheter or a riser of an endoscope or the like, possibly resulting in exfoliation of the resin coating layer.
In view of this, the proximal section of the resin coating layer has to be tapered so that the proximal end part of the resin coating layer is less likely to be caught by the distal end of the catheter used in combination with the guide wire, or by the riser of the endoscope used in combination with the guide wire.
Examples of the method for the tapering used hitherto include processing by use of a heat-shrinkable tube, physical processing by use of a grinding tool such as a grinder, and chemical processing by use of a solvent.
However, none of these processing methods has made it possible to relatively easily conduct adequate tapering.
In the processing by use of a heat-shrinkable tube, portions other than the portion to be tapered may also be affected by heat and be deformed.
Besides, in the processing by use of a grinding tool such as a grinder, fuzzing may be generated at the ground portion.
Further, in the processing by use of a solvent, it is difficult to control the quantity of the solvent, so that insufficient processing or excessive processing would occur.